1. Field of the Invention
This invention relates to signaling systems which may include instrument panel assemblies having means for permitting selective testing of the operability of the indicating means and/or alarm means thereof.
2. Description of the Prior Art
In instrument panel assemblies of the prior art, a plurality of indicating lamps or the like may be mounted to a panel for indicating different conditions of associated equipment. Illustratively, in a vehicle, the instrument panel may include a plurality of indicating lamps arranged to indicate abnormal conditions, such as high oil temperature, etc.
In the commercial automobile field, such indicator lamps are considered to be somewhat unreliable relative to protecting the associated equipment in that a burnout or loose connection of the particular indicator lamp causes a failure of indication to the driver of a malfunction of the apparatus of the vehicle. Illustratively, where the indicator lamp provided to signal a low oil level condition burns out, the driver of the vehicle may not be properly apprised of such condition, causing serious and costly damage to the engine.
In U.S. Pat. No. 3,745,547 of Walter Robert Hadank, a lamp supervisory circuit is shown having a test switch which is connected through a plurality of indicating lamps. The control includes a supervisory circuit which is connected through a plurality of diodes to a corresponding plurality of indicating lamps. The control includes a supervisory circuit which operates to indicate a component failure in one of the branch circuits of the lamp supervisory circuit. An alarm is provided for indicating when one of the lamps fails so as to avoid a failure of the indicating system to provide the desired indicating function.
Irving F. Weiss discloses, in U.S. Pat. No. 3,040,243, a test circuit for an indicator system having means for activating all the indicators of a control panel simultaneously to ascertain their operating condition.
Allan Bennett, in U.S. Pat. No. 3,631,393, shows a vehicle lamp failure warning system having a first lamp circuit for illuminating the lamp and a second lamp circuit which is completed when the lamp is extinguished but has a resistance sufficiently high to insure that the lamp is not illuminated.
Tobias Wagner discloses a motor vehicle control light system in U.S. Pat. No. 3,320,586 including a signaling device mounted at the rear of the vehicle where it may be seen by other drivers so as to advise as to the intentions of the driver of the vehicle.
In U.S. Pat. No. 3,975,708, Joe F. Lusk et al show a vehicle condition monitoring system providing status information regarding the operability of headlights or taillights and the condition of the following trailer. The system may also be used to check the tire pressure and brake drum temperature. A memory circuit is provided for storing a fault condition and a diagnostic unit may be used subsequently to detect the condition of the memory circuit.